Means for starting alternating-current machines.



N0- 830,947. PATENTED SEPT. 11, 1906. O. F. WHITEHURST. MEANS FOR STARTING ALTERNATING CURRENT MACHINES.

APPLICATION FILED JAN. 28, 1905.

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. wccy UNITED STATES PATENT OFFICE.

()Bl ll.) 1*. \VlllilEl-lUltS'l, OF SGHENECJTADY, NEW YORK, ASSIGNOR TO GEN- ERAL ELE I'lltlU COMPANY, A CORPORATION OF NEl/V YORK.

Specification of Letters Patent.

Patented Sept. 11, 1806.

Application filed January 28, 1905. Serial No. 243,034-

T!) 11.7/ 1071 0111 7 1 may concern:

Be it; known that I, Onni) F. VVIII'rEuuRs'r, a citizen of the United States, residing at Schenectady, county of Schenectady, State oi New York, have invented certain new and Useful improvements in Means for Starting Alternai'ing-Ourrent Machines, of which the following is a specification.

My invention relates to the control of alternating-current machines; and its object is to provide a novel arrangement ofstarting devices comprising an improvement in the arrangement ordinarily employed in such cases whereby greater simplicity and reduced 6311091180 RTE secured.

in starting up a large alternating-current motor or a generator which is started as a motor it is ordinarily desirable further to impress a reduced voltage on the motor in order to prevent the rush of current which would occur if the full voltage of the circuit wereimpressed on the motor at the start. One arrai'igcinent frequently employed heretofore consists in providing a compensator and voltage-lowering transformer with means for connecting the motor to two or more points on its winding. When only two voltages are required for starting and for running, respectively, each motor requires merely a doublethrow switch to connect it first to a point on the compensator or other voltage-regulator, sothat a reduced voltage is impressed upon the motor for starting and then when it is up to speed to connect it to the line to receive the full voltage. For large motors two voliages are frequently insuihcient for obtaining a gradual acceleration without an undue rush of current. If three voltages are required, the usual ractice is to connect the motor first to a low-voltage oint on the regulator, then to another po nt of higher vi'altage, and finally to the line. In this case it becomes necessary to employ two doublethrow switches for each machine, since the construction of a triple-throw switch in large sizes would be impracticable. Since for circuits of high voltage and large current capacity the switches are necessarily ex ensive, the cost of providing two oub e-throw switches for starting each machine is consid-v erabie.

By my invention I am enabled to eliminate one of the double-throw switches for each machine and nevertheless to obtain three different voltages. Toaccomplish this end, I wind the compensator or other voltage-regulator for a voltage somewhat higher than that of the li no to which it is to be connected, so that the line may be connected either to the total win ding or to only a portion thereof, and I provide means for connecting each machine either to a point on the compensator or to the liner-that is, I require a double-throw switch for the compensator and one doublethrow switch for each machine. The expense of one double-throw switch for each machine is thereby eliminated,- and this gain is offset only :by the necessity of substituting a doublethrow instead of a single-throw switch for the compensator, and. since one compensator and its switch may be employed for starting a large number of machines this offset is a practically negligible consideratiom My invention will best be understood by reference to the accompanying drawings, in which A and A represent two alternatingcurrent motors or generators, which are indicated as three-phase and which are to be started as alternating-current motors supplied from the threehase line or bus-bars B.

C re resents ayOl tage-regulater, which I have s lOWIl as of the single-coil or compensator type, star-connected; but it will be undestood that other forms of voltage-regulator may be employed, if desired.

S represents a double-throw switch adapted to connect the bus bars either to the upper terminals of the compensator or to intermediate points on the'winding.

S and S -represent double-throw switches adapted each to connect its'machine to an intermediate point on the winding of the compensator or to the bus-bars B.

In starting up the machine A the switches S and S are both thrown downward. The bus-bars B are thereby connected to the terminals'of the compensator C,'and the machine A is connected across a portion of the compensator-winding. A voltage is thereby impressed upon the machine A de endent upon the ratio of that portion of t e compensator to the entire winding. For the sec- 0nd voltage the switch Sis thrown upward, connecting the bus-bars B to a ortion only of the compensator-windings. 'lhe ratio of primar to secondary turns is thereby decrease and the voltage impressed upon the v b for the machines A and A, respectlvely, and

machine A is increased. For the third and final voltage the switch S is thrown u ward, thereby connecting the machine A irectly to the bus-bars B. The switch S may then be opened, disconnecting the compensator from the bus-bars B, or it maybe thrown downward for the purpose of starting up the second machine A.

It will be seenfrom the above'descrip'tionthat only a single double-throw switch 1s required for each machine and a double-throw switch for the compensator, while at the same time three different voltages'are available for starting each machine.

. machine, a circuit What I claim as new, and desire to secure by Letters Patent of the United States, is

1. In combination, an alternating-current to'which said machine is to be connected, a'voltage-regulator, means for impressing the 'voltage of said circuit upon the whole or upon a-portion of said regulator,

and means for connecting said machine to said regulator or .to said circuit independently of said regulator.

2. In combination,

machine, a circuit to which said machine is to be connected, a voltage-regulatorya doublethrow switchv adapted to connect the wholeor a portion of the winding of the regulator to said circuit, and a double-throw switch adapted to connect said machine to said regulator or to said circuit.

machines are to be an alternating-current 3. In combination, an alternating-current machine, a circuit to which said machine is to be connected, acompensator, a double-throw switch adapted to connect the whole or a p01'- tion of the winding of said compensator to "said circuit, and a double-throw switch adapted to connect said machine to a portion of said compensator-winding or to said circuit.

4. In combination, a plurality of alternating-curre'nt machines, a circuit to which said connected, a voltageregulator, a double-throw switch adapted to 45 connect the whole or aportion of sald regulator to said circuit, and a double-throw switch for each machine adapted to connect its machine to said regulator or to said cir-' cuit. .50

5. In combination, a plurality of alternating-current, machines, bus-bars, a compensator,-a doublethrow switch ada ted to con- .nect the whole or a portion of t e'compensator-winding to said busbars,and a doublethrow switch for each machine adapted to connectits machine to a portion of said compcnsatorswinding or to said bus-bars. In witness whereof I have hereunto set my hand this 27th day of January, 1905.

' OBED' F. WHITEHU R ST.

Witnesses:

BENJAMIN. B. HULL, HE EN ORFoRn. 

